Last but not at least the STRINGBIKEÂ® is a beautiful piece of art, and the reciprocating movements of the swinging members with the never ceasing winding of the ropes provide a nice visual impression.

Uhhh... this isn't a lever drive system. Watch the videos on the website.

The rider's feet move in circles (as if riding a bike with regular cranks), unlike the lever systems you've mentioned. For all intents and purposes, it looks like the rider wouldn't even notice the difference between this and a normal bike.

It looks cumbersome and complicated, but I'd give it a go. If a string were to snap, could it cut your leg?

For sure, the pedal action is not lever-style, it's rotary. However the drive is just the same as all the other lever-drives, just using string not chain. This type of drive has a number of disadvantages over the good old rotary chain.

I remain very sceptical

Riding bikes in traffic - what seems dangerous is usually safe; what seems safe is often more dangerous.